This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. UCSD will participate as one site in a multi center trial with the overall goal of conducting a comprehensive genome-wide association (GWA) study to identify genes influencing COPD. A list of all participating sites and the investigators is in Appendix A. Our primary hypotheses are: 1) Precise characterization of COPD subjects using computed tomography, as well as clinical and physiological measures, will provide insight that will enable the broad COPD syndrome to be decomposed into clinically significant subtypes. 2) Genome-wide association studies will identify genetic determinants for COPD susceptibility that will provide insight into clinically relevant COPD subtypes. 3) Distinct genetic determinants influence the development of emphysema and airway disease.